Internal combustion engine-electric power plant



' Aug. 4, 19 36. c. SCHAER 2,050,068

INTERNAL COMBUSTION ENGINE-ELECTRIC POWER PLANT 0 Filed March 17, 1933 2 Sheets-Sheet 1 1936- c. sci- AER 2,050,068

INTERNAL COMBUSTION ENGINE-ELECTRIC POWER PLANT Filed March 17, 1953 2 Sheets-Sheet 2 IF II I INVENTOR. 44% .744610 5 ATTORNEYS.

Patented Aug. 4, 1936 PATENT OFFICE INTERNAL COMBUSTION ENGINE- ELECTRIC POWER PLANT Charles Schaer, Langenthal, Switzerland, as-

signor to firm Sulzer Freres Societe Anonyme,

Winterthur, Switzerland Application March 17, 1933, Serial No. 661,239 In Switzerland March 22, 1932 4 Claims.

For internal combustion engines which drive an electric generator it is known to regulate the speed of. the internal combustion engine automatically to a substantially constant but adjustable value, in that alterations in load in the region of low loads are compensated by altering the fuel supplied, whilst alterations at higher loads are regulated by adjusting the excitation of the electric generator while the full quantity of fuel continues to be supplied during the regulating operation. This has the drawback that great fluctuations in speed are caused during the regulating operation, so that the regulating takes a long time to carry out.

It is advantageous at all loads not only to efiect by the regulating operation a quick alteration of the excitation of the electric generator, but also, in order to accelerate the termination of the regulating, to adjust the fuel delivery during the regulating operation. According to the invention this is effected not only by providing a control device, comprising a supply device dependent on the speed of the internal combustion engine, and a piping system connected with the supply device and automatically controlling, under the influence of a throttle position in the piping system, by means of. a power piston connected to the piping piston, a resistance regulating the excitation of the electric generator in such a way that the speed of the internal combustion engine keeps to a substantially constant but adjustable value, but also by a device dependent on the speed of the internal combustion engine adjusting during the regulating operation the regulating member for fuel delivery in a sense opposite to the speed fluctuations of the engine occurring during said operation. The power piston actuating the regulating resistance may, after cutting out the regulating resistance, act on the regulating member for fuel delivery, in order to reduce the fuel supplied from the value set to the consumption for no load.

The invention is illustrated diagrammatically and by way of. example in the accompanying drawings in which,

Fig. 1 is a diagrammatic view of an enginedriven electric generator set provided with a hydraulic speed-responsive device arranged to control both the engine fuel-regulating device and the device for controlling the resistance in the excitation circuit of the generator.

Fig. 2 is a similar view of a modification in which the adjustment of the operating speed of the set is made in a difl'erent manner, and, in addition, the parts are so arranged that continued movement of the resistance-controlling mechanism, after the resistance has been reduced to a predetermined value, effects an adjustment of the fuel-regulating device to reduce the fuel supply, and thus automatically enables the speed- 5 responsive device, or governor, to control the speed of. the set at light loads.

Fig. 3 is a diagrammatic view showing an engine-electric set wherein the resistance in the generator field is controlled by one speed-respon- 1 sive device and the fuel-regulating mechanism of the engine is controlled by another speedresponsive device, and A Fig. 4 is a view of an engine-electric set similar to the one shown diagrammatically in Fig. 2 15 and illustrating a modified means for adjusting the mechanism to produce a change in the torque of the engine without affecting the speed.

In the construction illustrated in Figure 1 the internal combustion engine I drives a main generator 2 and an auxiliary generator 3. Though in the construction shown the auxiliary generator 3 supplies the necessary current for the field winding 4 of the main generator 2, the excitation current for the main generator 2 may be provided by a shunt winding or from a separate source. The excitation current flowing through the field winding 4 is regulated, as hereinafter described, by means of a rheostati.

The engine I drives a pump 6 which tends to circulate pressure medium through a pressure pipe 1, to a return pipe I as shown by the arrows in full lines. A throttling point 8 in the pipe I can be adjusted by means of a valve 9 actuated by a lever I0 so as to vary the rate of flow of pressure medium from the pressure pipe I to the return pipe 1 The pressure pipe 1 communicates through a branch pipe I I with a cylinder containing a piston valve l2 which controls the flow of pressure medium from the pressure pipe I to a cylinder I3 containing a control piston ll operatively connected by a rod I5 to the contact arm ii of the rheostat 5. The pressure pipe I also communicates through a second branch pipe II with a cylinder I8 wherein can reciprocate a. subsidiary piston I9 operatively connected to the piston valve I2 and influenced in the upward direction by a loading spring 20 acting through a piston rod 2|. The rod 2| is pivotally connected by means of a link 22 to the fuel regulating device of a fuel pump 23.

The control apparatus, constituted by the pump Ii, throttling device 8, valve mechanism comprising the valve I2, subsidiary piston I9 and control piston I4, automatically regulates the ex- 55 citation current of the main generator 2 so that the speed of the engine 6 is maintained constant at the desired value, as hereinafter described.

The throttle valve Q is first set by the lever iii, if desired by remote control, in accordance with the speed at which the engine is to operate. When the load on the engine I! decreases due, for errample, to the load on the main generator 2 being decreased, the speed of the engine first increases so that the speed of the pump is increased accordingly. The rate of flow of medium through the throttle d from the pressure pipe T! will remain substantially constant so that the increase in the speed of the pump 6 will result in the pressure in the pressure pipe l increasing whereby the valve mechanism comprising the subsidiary piston is and piston valve 92 will be forced downwards against the action of the loading spring 20. The piston valve 02 will thus permit pressure medium to fiow into the cylinder is beneath the control piston it whereby this piston will be raised and the resistance 5 decreased. The excitation current of the main generator and therefore the load on the engine will, in this way, be increased and the speed of the engine restored to the desired value in accordance with the setting of the throttle valve 9. The speed of the pump 9 being thus decreased will result in the pressure in the pipe I falling to the original or normal value so that the piston is will rise under the action of the spring 20 and the piston valve [12 will be returned to its normal or central position shown wherein it cuts oil the supply of pressure medium to the control cylinder i3.

When the load on the engine 6 increases, the speed of the engine and therefore the speed of the pump 6 decreases so that the subsidiary piston l9 and piston valvel2 rise from the normal positions shown in Figure. 1. Pressure medium there-r upon enters the cylinder 89 above the control piston H whereby the resistance 5 is increased and the load on the engine decreased. The speed of the engine i is in this way restored to the desired value whereupon the subsidiary piston I9 and valve l2 return to their normal or central positions shown. Pressure medium displaced from the cylinder l9 returns through the pipe 1 to the pump 9.

When the subsidiary piston l9 and valve l2 move-downwards or upwards due to an increase or decrease respectively in engine speed as above described the resulting movement of the lever 22 simultaneously reduces or increases the quan tity of fuel supplied to the engine. The regulation of the plant to restore the engine speed to the desired value is thus effected by simultaneously adjusting the load and the fuel supply- After adjustment of the valve 9 there will be a corresponding pressure on the inlet side of the throttle 9 for anygiven engine speed. Since however the quantity of medium which can flow through the throttle 8 is in accordance with the setting of the valve 9 the larger the opening of the throttle valve 9 the greater will be the speed at which the engine will be maintained by the control apparatus. The valve I: will occupy the central or normal position shown, 1. e., when it cuts oil the supply of pressure medium to the cylinder II, at a given normal pressure within the pressure pipe 1 that is to say a pressure which balances against the spring 20 when the piston I9 is in the central or normal position shown in the drawings. Thus, by v rying the setting of the speed necessary to produce the said normal presvalve 9 the engine ously with this adjustment accuses sure in the pressure pipe l will be adjusted ac-- cordingly. Since the engine speed necessary to centr the piston l9 and valve 62 is thus dependent not only on the setting of the valve 9 but also on the tension of the spring 29 adjustment of the speed at which the engine is to operate may be effected by varying the tension of the spring 20 instead of or inaddition to adjustment by means of the valve 9.

If desired, the piston i9 may be employed exclusively for actuating the valve 52 and the fuel supply regulated by means of a centrifugal governor at (Fig. 3) driven in accordance with the speed of the engine by gearing St, the tension of the spring 52 loading the governor 50 being simultaneously adjusted preferably through mechanism 53 operatively connected to the lever l9. With a view to limiting the maximum speed of the engine, the spring 52 may load the governor 59 in such a way that the governor 50 acts as a maximum speed safety regulator, cutting ofi or reducing the fuel supply automatically, if necessary, to the idle running value when the number of revolutions per minute of the engine exceeds a predetermined permissible maximum.

Further, instead of a positive pressure being employed in the pressure pipe 1 to actuate the pistons i9 and M a pump, such as the pump 6, may tend to pump the medium in the reverse directlon shown by the dotted arrows so that the pressure in the pressure pipe l will decrease in accordance with the increase inthe speed of the engine thereby operating the pistons l9 and I4 to produce the desired regulation.

In the construction throttling point 9 is not adjustable and the valve i2 is connected to the subsidiary piston l9 by a rod 26 through a lever 26 pivoted at 21 on a block which is internally threaded to engage a correspondingly threaded spindle28 rotatable by means of a gear 29 so as to adjust the speed at which it is desired that the engine is to be maintained, as hereinafter described. The lower end of the rod 25 is plvotally connected to a lever 99 which is in turn connected by a link 9| to the member 22 whereby the fuel supplied by the fuel pump 29 can be adjusted. The free end 92 of the lever 99 engages a slot in the adjacent end of a lever 99 pivoted on a fixed pivot 94 and connected to a rod 95 which is longitudinally slidable in a sleeve 96 carried by the contact arm IS. The rod 95, which is furnished at its upper end with a stop 91, is loaded by acompression sprlng98, the lowermost limit of movement of the rod 95 and therefore of the stop 91 being determined by a second stop 99. The piston valve l2 controls ports in a sleeve which can be adjusted axially by means of an operating rod ll.

Assuming that the parts are in the positions shown in Figure 2, l2 closing the ports in the sleeve 49, and the speed of the engine increases due, for'example, to a decrease in the load on the main generator the pressure in the pressure pipe I and therefore in the branch pipe reference to Figure 1. The piston l9 move upwards against the action of the spring 29 whereby the lever 26 will move the rod 25 downwards. The piston valve I2 is thus inoved to admit pressure medium to the-cylinder H below the control piston I which will thus rise and turn the contact arm 19 to reduce the resistance 5 and in this way increase the load on the engine thereby tending to reduce its speed. Simultanewill now illustrated in Figure 2 the 35 that is to say, with the valve 0 I1 will rise as described with 55 of the load the down- 7 I v the engine is that which ward movement of the rod 25 will act through the link 3| to reduce the fuel supply. The speed of the engine having been thus restored to the desired value the parts will return to their central or normal positions shown. In the event of the engine speed decreasing the sequence of operation of the parts will be the reverse of that above described.

The speed at which the control apparatus is to maintain the engine can be adjusted as desired by means of the gear 29, which may be operated by remote control apparatus. Thus, the speed at which the engine is to be maintained can be increased by turning the spindle 28 so as to raise the pivot point 21 of the lever 26 whereupon the speed of the engine necessary to produce a pressure in the pipe I! sufiicient to move the valve l2 into its central or normal position will be higher, the position of equilibrium being indicated by the position I of the lever 26. Adjustment of the pivot point 21 in this way simultaneously sets the fuel supply to suit the new operating speed of the engine. When it is desired to decrease the speed at which the engine is to be maintained the spindle 28 is turned to lower the pivot point 21 and therefore decrease the engine speed necessary to produce the pressure in the pipe H which will move the valve l2 into its normal or central position. The position of equilibrium is then indicated by the position II of the lever 26.

When the speed of the engine increases, due for example to a decrease in the load on the main generator, the upward movement of the piston ll, previously described, causes the block 36 to be moved upwards along the rod until the block 36 engages the stop 31 the arm I6 being in the position III on the resistance 5 which is thus a minimum. If upward movement of the block 36 continues the rod 35 will be moved upwardsthe spring 38 and the pivot point 32 of the lever 30 will be moved downwards thereby turning the member 22 so as to reduce the fuel supply. The arrangement is therefore such that when the resistance in the excitation circuit of the main generator has been reduced to the minimum value, 1. e., when the contact arm commences to move over the contact 62, the fuel supply is automatically reduced. In this way, in the event of the load on the engine continuing to decrease after the limit of load adjustment by means of the resistance 5 has been reached, increase of the engine speed is checked by reducing the supply of fuel, this decrease in the fuel supply continuing with decrease of the load, if necessary, until the quantity of fuel supplied to corresponds to idle runagainst the action of ning.

The engine torque may be adjusted, without changing the engine speed, by moving the sleeve valve M! in the axial direction so as, in effect, to vary the position of the piston valve l2 relatively to the ports through which the pressure medium flows to and from the cylinder l3. The normal or central position of the valve l2 and therefore of the lever 30 and member 22 corresponding to the desired speed of the engine are in this way adjusted. If desired, however, the engine torque may be adjusted by adjusting the operative connection between the member 22 and valve 82. To this end the rod 25 in Fig. 4 is divided into two parts screwed in the female screw 55 which may be turned by the rack 56 connected to the lever 51. By turning the screw 55 the rod 25 is shortened and lengthened, consequently the lever 30 and the member 22 are in this way adjusted corresponding to the desired speed of the engine.

In a power plant according to the invention the torque on the engine will be maintained substantially constant in spite of variations in the load on the main current generator, the speed of the engine being maintained substantially constant at any value desired with the result that overloading of the engine is prevented. Further, since the pressure medium is constantly circulated through the pipes I and 1 opening of the valve l2 will result in an immediate effect on piston l4 so that the resistance 5 will be adjusted without delay, which would tend to occur if the pressure medium in the pressure pipe I were maintained at rest while the valve i2 is in its central or normal position. Any appreciable variation in the load on the main generator is thus followed so rapidly by adjustment of the excitation current of the main generator that fluctuations in the hauling power or draw-bar pull, with 20 speed of the engine not only is the desired regu- 25 lation rapidly effected but, in addition, fluctuation of the engine speed is maintained within a small range.

I claim:

1. In combination, an engine, a generator driven thereby, a resistance for regulating the excitation current of said generator, a device for controlling said resistance including fluid supply means dependent upon the engine speed, a fluid circulating system connected with said fluid supply means and a power piston connected with said fluid circulating system for controlling said resistance, a fuel-regulating device, a device responsive to the speed of said engine, means for operatively connecting said speed-responsive device with said resistance-controlling device and said fuel-regulating device to cause the latter to be set during the regulating operation in a sense opposite to the speed fluctuation of said engine occurring during said operation, and means operatively connecting said resistance-controlling device and said fuel-regulating device, said means being operable only after a predetermined amount of said resistance has been cut out so as to reduce the fuel supply to said engine when the load thereon is below a predetermined value.

2. In an engine-electric set including a generator, a resistance for regulating the excitation of the generator, a control device including fluid supply-means dependent upon the engine speed, a fluid-circulating system connected with said fluid supply-means, a power-piston connected with said fluid-circulating system for controlling said resistance, a fuel regulating device for the engine, a pressure-responsive device connected to said system for actuating said fuel-regulating device, and means for adjusting the torque of the engine independently of the engine speed.

3. In an engine-electric set including a generator, a resistance for regulating the excitation of the generator, a control device including fluid supply-means dependent upon the engine speed, a piping system connected with said supplymeans, a power-piston for controlling said resistance, a control valve for connecting said power-piston with said piping system, a fuel-regulating device for the engine, a device responsive to the speed of the engine for setting said fuel-regulating device during the regulating operation in a sense opposite to the speed fluctuation of the able ports for said control valve and means for adjusting the position thereof.

4. In combination, an engine, a generator driven thereby, a resistance for regulating the excitation current of said generator, a device for controlling said resistance including fluid supplymeans, a piping system connected with said supply means, a power-piston in the piping system, and a control valve for connecting said powerpiston with said piping system, a fuel-regulating device, a device responsive to the speed oi said engine, means for operatively connecting said speed-responsive device with said control valve and said fuel-regulating device to cause the latter to be set during the regulating operation in a sense opposite to the speed fluctuation of said engine occurring during said operation, and means for adjusting the torque of the engine independently of the engine speed comprising means for adjusting the position of said control valve so as to cause said valve to open earlier or later with 10 "respect to the movement of said fuel-regulating device by said speed-responsive device.

CS SGHAER. 

